This application relates to dual mode document imaging systems, for either scanning a stationary document with a moving document imager on a large fixed platen or feeding documents past an imaging station on an adjacent smaller platen with the same document imager held stationary.
In the disclosed embodiment the smaller platen is mounted to allow vertical movement, to allow for different thickness of documents being fed to that platen yet allow the use of a fixed axis of rotation substantially constant velocity document transport. That can cause different bottom surface levels of the two platens. As disclosed, thin flexible transition members bridge the outer edges of the gap between the lower surface of the vertically movable smaller platen and the lower surface of the fixed platen to allow the document imager to laterally slide freely, on focal distance maintaining slide pads, across a small gap between the bottom surface of one platen and the bottom surface of the other, with the document imager being spring biased upwardly towards the lower surfaces of both platens.
By way of background, various types of dual mode document handlers (document feeders and imagers) and platen scanners are known in the art. The following patent disclosures are noted by way of some examples: Xerox Corp. U.S. Pat. No. 5,339,139, issued Aug. 16, 1994, xe2x80x9cDocument Feeder with Positive Document Removal From Imaging Platenxe2x80x9d by Jack K. Fullerton, et al; Xerox Corp. U.S. Pat. No. 5,680,204, issued Oct. 21, 1997, xe2x80x9cDual Scanning Electronic Reprographic Document Handlerxe2x80x9d by Joseph J. Ferrara; and Xerox Corp. U.S. Pat. No. 5,012,275, issued Apr. 30, 1991, xe2x80x9cRight-to-Left Scanning System for Copying Documents or Bound Booksxe2x80x9d by Edward C. Bock. An example of typical prior art on having the optics unit ride on fixed rails, with no other connection to, or control by, the platen or image plane position, is disclosed in Xerox Corp. U.S. Pat. No. 4,982,236, issued Jan. 1, 1991, entitled xe2x80x9cSelf Supporting Optical Document Scanning Systemxe2x80x9d by Edward C. Bock.
Of particular interest to the subject of full width array document scanning system in which the imaging unit has slide pads engaging the bottom surface of the document platen glass are Xerox Corp. U.S. Pat. No. 5,778,277 issued Jul. 7, 1998 to Stephen J. Wenthe, Jr., et al and U.S. Pat. No. 5,659,405 issued Aug. 19, 1997 to Charles F. Prevost, et al.
Further by way of background, and as illustrated in the cited and other art, low cost scanners or copiers with automatic or semi-automatic document feeding by document handlers may have a rigid or fixed axis substantially constant velocity transport (CVT) document feeding roll, and a small platen glass under the CVT roll to provide for the image positional alignment of the document being fed and scanned by an imager held stationary under that small platen at that imaging position while the documents are fed over the top of that small platen. Typically, the optics for these scanners or copiers have been half rate systems riding on fixed rails with a light lens and a CCD digital imaging array, because such low cost scanners or copiers often also desirably have a much larger adjacent platen for individually scanning stationary documents with that same optics unit. That is, scanning the documents manually placed on that larger platen with moving optics. If the smaller adjacent CVT fed documents imager platen would be vertically spring loaded for floating (to accommodate different thickness documents being fed), a vertical step difference would occur between the large fixed platen used for manual document scanning and the floating platen of the document feeder. However, that would not allow full width array (FWA) or other optics units or modules to instead ride on or be guided by the bottom side of the platen to maintain the depth of focus. That requires both platens to be the same or integral rigidly held glass having and maintaining the same bottom plane. To accommodate different thickness documents with such a fixed platen would require a floating or variable axis position CVT instead of fixed CVT roll in the document handler. However, a floating CVT requires a flexible drive connection which adds complexity and may vary the desired constant velocity needed for uniform imaging of the moving document.
A specific feature of the specific embodiment disclosed herein is to provide a dual mode document handler in which documents may be imaged by the same document imager by (a) scanning a document on the upper surface of a large stationary document platen by moving said document imager under the lower surface of said larger stationary document platen, or by (b) feeding documents with a document transporting system past a moving documents imaging station on the upper surface of a smaller platen with said document imager positioned under the lower surface of said smaller platen, wherein the documents are fed by said document transporting system to said upper surface of said smaller platen, the improvement comprising mounting said smaller platen adjacent to but independently movable relative to said larger stationary document platen with a small gap in between said smaller platen and said larger stationary document platen, biasing said smaller platen for said independent movement towards said larger stationary document to allow different spacing of said upper surface of said smaller platen from said document transporting system for different thickness of said documents being fed from said document transporting system to said upper surface of said smaller platen, providing a flexible transition member bridging said gap between said lower surface of said smaller platen and said lower surface of said larger stationary document platen, said document imager being biased towards said lower surface of said smaller platen and said lower surface of said larger stationary document platen, and said document imager having platen engagement members allowing lateral movement of said document imager relative to said lower surface of said smaller platen and said lower surface of said larger stationary document platen and said flexible transition member, said platen engagement members maintaining the document imaging focus of said document imager relative to both said independently movable smaller platen and said larger stationary document platen.
Further specific features disclosed in the embodiment herein, individually or in combination, include those wherein said document transporting system comprises at least one document drive roller adapted to be rotatably driven at a substantially constant velocity on a fixed axis of rotation, and/or wherein said platen engagement members comprise plural low friction slide pad members, and/or wherein said flexible transition member comprises thin flexible strips adhered to adjacent areas of said lower surface of said smaller platen and said lower surface of said larger stationary document platen, and/or wherein said flexible transition member comprises thin flexible strips of MYLAR(copyright) adhered to adjacent areas of said lower surface of said smaller platen and said lower surface of said larger stationary document platen on opposite sides of said moving document imaging station, and/or wherein said platen engagement members comprise plural low friction slide pad members slidable on said lower surface of said smaller platen and said lower surface of said larger stationary document is platen and said flexible transition member, and/or a dual mode method of document imaging with a document handler in which documents may be imaged by the same document imager by scanning a document on the upper surface of a large stationary document platen by moving said document imager under the lower surface of said larger stationary document platen, or alternatively, feeding documents with a document transporting system past a moving documents imaging station on the upper surface of a smaller platen with said document imager positioned under the lower surface of said smaller platen, mounting said smaller platen adjacent to but independently movable relative to said larger stationary document platen with a small gap in between said smaller platen and said larger stationary document platen, biasing said smaller platen for said independent movement towards said larger stationary document to allow different spacing of said upper surface of said smaller platen from said document transporting system for different thickness of documents being fed from said document transporting system to said upper surface of said smaller platen, providing a flexible transition member bridging said gap between said lower surface of said smaller platen and said lower surface of said larger stationary document platen, said document imager being biased towards said lower surface of said smaller platen and said lower surface of said larger stationary document platen, and said document imager having platen engagement members allowing lateral movement of said document imager relative to said lower surface of said smaller platen and said lower surface of said larger stationary document platen and said flexible transition member, said platen engagement members maintaining the document imaging focus of said document imager relative to both said smaller and independently movable platen and said larger stationary document platen, and/or wherein said document transporting system comprises at least one document drive roller adapted to be rotatably driven at a substantially constant velocity on a fixed axis of rotation, and/or wherein said platen engagement members comprise plural low friction slide pad members slidable on said lower surface of said smaller platen and said lower surface of said larger stationary document platen and said flexible transition members.
As to specific components of the subject apparatus or methods, or alternatives therefor, it will be appreciated that, as is normally the case, some such components are known per se in other apparatus or applications, which may be additionally or alternatively used herein, including those from art cited herein. For example, it will be appreciated by respective engineers and others that many of the particular component mountings, component actuations, or component drive systems illustrated herein are merely exemplary, and that the same novel motions and functions can be provided by many other known or readily available alternatives. All cited references, and their references, are incorporated by reference herein where appropriate for teachings of additional or alternative details, features, and/or technical background. What is well known to those skilled in the art need not be described herein.